Statement on Heat Storm and Rolling Blackouts
CESA members should be aware that the ongoing heat-storms and rolling blackouts in California are an important moment in the California electric system. While it is difficult to guess ‘what will all this mean for the grid moving forward?’, here is a reasonably informed opinion.
First of all, buckle down for the next few days and contribute as you can, either by managing your electricity usage or ensuring your energy storage solutions are being usefully operated, e.g. to deliver energy and services during the peak, especially as the solar production drops off. Today (August 17, 2020), we expect the CAISO will have rolling blackouts and serious capacity deficiencies for meeting electrical needs by 4400 MW. For context, there are only 200 MW of new energy storage on the system right now, and a 4400 MW deficiency is extremely concerning!
How is energy storage responding in this crisis?
The data shows that energy storage has been actively helping to meet grid peak needs. Recall that for now, energy storage remains a VERY small part of the state’s grid. The CAISO system saw needs for generating capacity of around 50,000 MW, but the storage components on the grid are only about 200 MW in operation today, aside from the decades old pump-hydro units (another 2,000 MW or so).
CESA researched the performance of modern storage during the heat storms and saw generally good performance, but also that the extended duration of the hot period and persistently high grid needs did eventually deplete storage units, which then needed to recharge after the peak.
Graph 1 shows the load and the net load (left Y-axis) and the operation of storage resources (right X-axis). Note that negative observations in the storage trend represent charging and positive observations represent discharging. As can be seen, storage resources continuously discharged during the Stage 2 Emergency period, and even during some of the intervals of the Stage 3 Emergency. However, eventually, around 8 PM PDT, modern storage resources were depleted and required charging.
In many ways, this is expected, but we should expect some discussions relating to storage duration. CESA supports deploying energy storage solutions that meet grid needs, and this will include many types of storage with capabilities ranging from short duration, 4-hour duration, and longer-durations, which may include 6, 8, 10, and 12+ hour or even multi-day storage solutions. This philosophy and our storage tech-neutral approach are informing our RA and IRP advocacy efforts that are actively underway.
Why is the grid under such strain?
For more information on this situation from the CAISO, you can read their presentation here. However, there are a few explanations that CESA looked into.
1. Could this be from bad forecasting of the weather and related electrical usage within the Day-Ahead (DA) market? Probably not. CESA analyzed the variations between DA load and actual load to determine if scheduled resources resulted insufficient and triggered the emergency. CESA found that, for the 4 to 10 PM period, actual load was 3% smaller than DA forecasted load for August 14, though this analysis also includes some of the load curtailments. Table 1 compares this deviation with the rest of the week, for context.
2. Another potential explanation is variations in load shapes due to the Covid-19 pandemic. Differences in the timing of load could impact the availability of low-cost electricity, which is essential to charge storage resources. To test this case CESA compared the load of this past week to its 2019 homologue, Graph 2 shows the difference for Friday. Graph 2 shows higher load in 2020 during all hours after 9:00 AM, including the window of the highest solar PV generation. This load shape suggests more low-cost renewable electricity was serving load rather than being available to charge storage.
3. Finally, we will analyze if the CAISO may have underestimated needs in its month-ahead Resource Adequacy ‘true-up’ process. If an underestimation in this period occurred, it may have allowed some generating units or transmission to take outages and to be unavailable or otherwise contracted during the heat storm.
4. Imports from out-of-state resources may have failed to deliver.
Table 1: Difference between Day-Ahead load forecast and actual load during the 4 – 10 PM period
What can we expect when the heat storm is over?
By this Thursday, the grid will very likely be back to normal operation. When this heat-storm is over, here is what may reasonably expect to occur with relevant agencies:
Accelerated and more conservative grid planning.
The CPUC will likely need to consider and eventually authorize accelerated procurements of energy storage but will also be forced to consider what gas plants need to be retained near-term, and if/how to hybridize them with storage.
A focus on the urgency for more energy storage portfolio diversity and additional longer-duration storage.
An evaluation of the CPUC RA program and potential changes to that program (join our RA Working Group to learn more).
The CAISO will likely take a more outspoken and forceful posture about its needs. This will show up as more vocal CAISO skepticism towards energy efficiency and demand response, expressions of desire for more storage and longer-duration storage, and more willingness to give ‘backstop’ contracts to older or uncontracted gas units.
Finally, some blame will get placed on the role of imports in planning. The CAISO is actively sharing data on imports as I write this, and I expect there will be less trust in unspecified imports going forward.
What is CESA’s plan moving forward?
Given these potential outcomes, CESA will work to emphasize that storage is here to help, that we’re still a tiny part of the system, and that aggressive high-volume procurement is needed of storage, along with a rapid expansion of our storage portfolio to include diverse storage solutions to support reliability.
We will also emphasize how planners should focus on real contracts and should be conservative in ensuring RA resources are known and contracted. CESA will also, where appropriate, emphasize how we have prudently pushed to get storage contracts approved expeditiously, and to add diversity to the storage fleet. We will advocate aggressively to highlight how our recommended storage adoption timelines and strategy will promote reliability and mitigate these types of capacity shortfalls with clean energy solution that address evening peak needs.
We at the CESA team hope you are safe and well during this very serious time. We recognize that power outages during a heat-storm can be life-threatening. At the same time, we will work to understand very specifically how this all happened, what key actions or assumptions led to it, and how we can avoid it going forward. Of course, once this heat wave ends, we will be entering serious wildfire conditions where PSPS could occur, so the attention and focus of the public could be diverted.
Input from CESA members is welcome, and rest assured that we at CESA are working diligently to support our mission of ensuring energy storage is properly deployed and valued in the state’s electric system.
Sincerely,
Alex Morris and the CESA Team